Semantic definitions at the entity

Entity definition

IfcProject indicates the undertaking of some design, engineering, construction, or
maintenance activities leading towards a product. The project establishes the context for information to be exchanged or shared, and it may represent a construction project but does not have to. The IfcProject's main purpose in an exchange structure is to provide the root instance and the context for all other information items included.

The context provided by the IfcProject includes:

the default units

the geometric representation context for exchange structures including shape representations

the project coordinate system

the coordinate space dimension

the precision used within the geometric representations

optionally the indication of the true north

optionally the map conversion between the project coordinate system and the geospatial coordinate reference system.

HISTORY New entity in IFC1.0

IFC4 CHANGE The attributes RepresentationContexts and UnitsInContext are made optional and are promoted to supertype IfcContext.

Informal Propositions:

There shall only be one project within the exchange context. This is enforced by the global rule IfcSingleProjectInstance.

Formal Propositions

Rule

Description

HasName

The Name attribute has to be provided for IfcProject. It is the short name for the project.

Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups.

References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical strutures only).

IFC4 CHANGE The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition.

References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types).

IFC4 CHANGE The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition.

References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definitions can be aggregated by several other objects (occurrences or parts).

References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definitions can only be part of a single decomposition (to allow hierarchical strutures only).

Context of the representations used within the context. When the context is a project and it includes shape representations for its components, one or several geometric representation contexts need to be included that define e.g. the world coordinate system, the coordinate space dimensions, and/or the precision factor.

IFC4 CHANGE The attribute has been changed to be optional. Change made with upward compatibility for file based exchange.

The representation context of the project refers to a global positioning, i.e. the local engineering coordinate system of the project has a mapping to a defined projected coordinate system (a rectangular map coordinate system, as used in GIS systems)

The IfcProject is also the context for other information about the construction project such as a work plan. Non-product structures are assigned by their first level object to IfcProject using the IfcRelDeclares relationship. The IfcProject provides the context for work plans (or other non-product based) descriptions of the construction project. It is handled by the objectified relationship IfcRelDeclares.

The IfcProject is used to reference the root of the spatial structure of a building or other construction project (that serves as the primary project breakdown and is required to be hierarchical). The spatial structure elements are linked together, and to the IfcProject, by using the objectified relationship IfcRelAggregates.

The following constraints are applied to using the relationshio IfcRelAggregates in context of IfcProject

NOTE The anomaly to use the composition structure through IfcRelAggregates for assigning the uppermost spatial container to IfcProject is due to upward compatibility reasons with earlier releases of this standard.

IfcProject.Decomposes -- it shall be NIL, i.e. the IfcProject shall be on top of the root of the spatial structure tree.